Currently, the semiconductor industry is demanding faster and denser devices (e.g., 0.05-.mu.m to 0.25-.mu.m) which implies an ongoing need for low resistance metallization. Such need has sparked research into resistance reduction through the use of barrier metals, stacks, and refractory metals. Despite aluminum's (Al) adequate resistance, other Al properties render it less desirable as a candidate for these higher density devices, especially with respect to its deposition into plug regions having a high aspect ratio cross-sectional area. Thus, research into the use of copper as an interconnect material has been revisited, copper being advantageous as a superior electrical conductor, providing better wettability, providing adequate electromigration resistance, and permitting lower depositional temperatures. The copper (Cu) interconnect material may be deposited by chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PECVD), sputtering, electroless plating, and electrolytic plating.
However, some disadvantages of using Cu as an interconnect material include etching problems, corrosion, and diffusion into silicon..sup.1 These problems have instigated further research into the formulation of barrier materials for preventing electromigration in both Al and Cu interconnect lines. In response to electromigration concerns relating to the fabrication of semiconductor devices particularly having aluminum-copper alloy interconnect lines, the industry has been investigating the use of various barrier materials such as titanium-tungsten (TiW) and titanium nitride (TiN) layers as well as refractory metals such as titanum (Ti), tungsten (W), tantalum (Ta), and molybdenum (Mo) and their silicides..sup.2 Although the foregoing materials are adequate for Al interconnects and Al-Cu alloy interconnects, they have not been entirely effective with respect to all-Cu interconnects. Further, though CVD has been conventionally used for depositing secondary metal(s) on a primary metal interconnect surface, CVD is not a cost-effective method of doping Cu interconnect surfaces with calcium (Ca) ions.
 FNT .sup.1 Peter Van Zant, Microchip Fabrication: A Practical Guide to Semiconductor Processing, 3.sup.rd Ed., p. 397 (1997).
 FNT .sup.2 Id., at 392.
Some related art methods for forming metal oxide films as barrier materials generally include two electrochemical approaches: (1) electrochemical oxidation using an external electrical current (e.g., La.sub.1-x Sr.sub.x MnO.sub.3 and LaCoO.sub.3); and (2) electroless deposition (i.e., that which does not require an electrical current to drive the reaction (e.g., PbO.sub.2, MnO.sub.2, Tl.sub.2 O.sub.3, NiO, LaMnO.sub.3). Therefore, a need exists for a low cost and high throughput method of forming a Cu--Ca--O thin film on a Cu surface in a chemical solution which improves interconnect reliability, enhances electromigration resistance, and improves corrosion resistance.